I'm just sort of picky about alignment when I set up. But I've heard lots of stories about people not compensating when shooting a rig with greater sight height than what they are accustomed to using. (ouch) I usually eyeball off the bench to see what the barrel would have to line up on to give appropriate clearance, then figure out how much to add for the height of the sights and see what's in the background at that height, then aim at that point. Usually only get close to getting in trouble when shooting pistols for a quick check -- don't bench them, and have to remember not to move around to keep my background reference point in the correct location.